Expanding bit



Nov. 17, 1931. s. c. KNAUR EXPANDING BIT Filed June 29. 1929 r r Y rlgsw f will@ f V Patented Nov. 17, 1931 pasaras EXPANDING BrrApplication led June 29,

My invention relates to drills for use in deep well drilling for oil,gas, water, sulphur and the like.

In deep well drilling a large item of eX- pense is incurred inwithdrawing the drill from the hole to sharpen or replace the cutters.Where the hole is deep it sometimes happens that a third of the time isthus consumed. This is not only expensive in the extra amount necessaryto pay the drilling crew, but also in the time wasted where productionshould be obtained.

It is an object of myinvention to provide a drill that may be withdrawnfor sharpening or replacement in a minimum of time without the necessityof removing the drill stem.

I contemplate the removal of the drill by means of a cable which may bereeled up quickly. The drill to which the cable may be engaged isadapted to collapse within the drill stem so that it may be readilyremoved.

It is a iurtherobject to provide a. reaming bit, to be employed with apilot bit, the

cutters of the reamer being easily and pos'- itively expanded, and ofsimple construction so that the device is cheap and economical tomanufacture and'not liable to get out oi order or tail to functionpositively at all times. I desire to eliminate springs or levers orsimilar elements which might get clogged or jammed and thus fail in use.

In the drawings herewith Fig.' 1 is a central longitudinal sectionthrough a device F embodying my invention, the expanding elements being`in cutting position at the lower end of the drill stem.

Fig. 2 is a broken detail illustratinsr the cutting blades in contractedposition where they may be withdrawn through the drill stem to thesurface.

Fig. 3 is a broken detail in elevation illustrating the manner in whichthe blades-are supported during rotation.

In constructing my device I connect at the lower end of a drill stem l ashoe 2, which is of slightly heavier construction than the drill stemand is formedto cooperate with my expanding bit. The inner diameter ofthe shoe is decreased slightly over that of Cil 1929. serial No.374,808.

the drilll stemy to form aV shoulder upon which a drill nipple 4 may besupported. The lower end of the shoe is formed with two approximatelyopposite downwardly extending arms 5..'1As seen in Fig. 3, these armsmay be beveled forwardly Vat 6 although this is not 'a necessaryfeature.

The drill which I employ may bea fish tail bit or any common type ofdrill `which may be preferred. I have shown a shytail bit 7 as havingthe usual threaded connection with the lower end of the drill nipple4,previously referred to. Said drill nipple is of tubular construction.It has a peripheral flange 8 spaced slightly from the upper 35 f end,said flange being adapted to engageupon the shoulder 3 in the shoe andis supported b v gravity thereon.

Spaced slightly above the pilot bit I pro- .v. vide'a plurality ofexpanding cutter blades 9, Said blades are approximately triangular inshape and are pivotally supported upon pins 10 extending through theupper ends of said blades' andfthrough the walls of the slots 11 in thenipple. in which said blades are 75 mounted. The slots 11 in the nipple,which accommodatev the blades, are of vsufficient width to allow freemovement of the blades therein. the slots .being approximately ,oppositebut slightly offset so that when the blades are moved inwardly tocontracted position. as shown in Fig. 2,#thelv may nass each other andoverlap to some extent. It is to be noted that the "inner si des ot' theblades. indilf cated'at 12.` are straight so that thev mav con.- tactwith an inner expanding mandrel 13. y The mandrel 13 is adapted toproiect above the nipple 4 and mav be provided with a head i anypreferred construction. wherebv it mav be engaged bv a setting tool orsimilar device so that it may be lowered into the well and released and'asrainv engaged :tor withdrawal. Setting tools adapted for thispurposeare of ordinary and common construction and need not be shown. iThe mandrel is of suitable outer diameter to lit slidably within thenipple Ll. The lower end of the mandrel is flattened slightly/ron eachside at l5 to'abut against the inner sides l2 of the blades so as 100and the nipple l is provided by means of a transverse pin 16, which issupported within the walls of the nipple l and extends dia.-

metrically through slots 17 formed in the opposite sides of the mandrel.Each slot 17 is accurately positioned relative to the blades so as toallow suliicient longitudinal play or sliding movement of the mandrelrelative to the nipple so that when the mandrel vis drawn upwardly, soas to bring the lower end of the slot 17 in contact with the pin, asshown in Fig. 2, the lower end of the mandrel will be entirely free ofthe cutters so that they may be moved inwardly Vinto retracted position,the length of the-slotbeing sufficient. however, so that when theVmandrel is lowered between the cutters, as shown in Fig. 1. the pin 16will be toward the upper limit of the slot. A

It is to be noted also that when the nipple 4 is in position with-theiiange 8 resting upon the shoulder B in the shoe, the slots '11 in whichthe blades are mounted, will `be sufiici'ently beyond the lower end ofthe shoe so as to allow the blades to be projected outwardly. When saidblades are thus projected,

as into the position shown in Fig. 1, the outer edgesof the blades willcome into contact with the lower beveled shoulders 18 upon the shoe,thus limit-ing the outward movement of the blades and clamping` saidblades rigidly between the lower end of the mandrel and the inner wallof the shoe. Also. when the drill stem is rotated in the usualright-hand direction` the arms 5 upon the shoe will engage against therearward sides of the blades and exert a driving action thereon andsupport them from the rear.

The operation of my device will now be understood. The drill stem may beintroduced into the hole andmay remain there throughout the drillingofthe'well. The bit.J including the pilot drill 7 andthe expanding blades8, may be lowered into the well to cutting position. While the device isbeing thus lowered the nipple and the bits will be supported from themandrel and the weight of the nipple willmove the pin 16 in the saidnipple to the lower end of the slot 17 in the mandrel andthe blades willbe contracted below the mandrel, as seen in Fig. 2. When the bottom ofthe well has been reached the bit will rest upon the bottom of theA holeand the weight of the mandrel will move said mandrel downwardlyrelative'to the nipple, contacting with the inner edges of the bladesand forcing saidblades outwardly to the position shown in Fig. 1. Theflattened sides of the mandrel will engage between the blades and form arigid and firm support for said blades on their inner sides and theouter edges of the blades will be clamped against the shoe. ,'When theblades are thus expanded it will be seen that a downward pressure uponthe drill stem will be exerted against the blades and a driving torquewill be exerted against the rearward sides of the blades to move themwith the drill stem to cut the wall of the hole. The pilot drill 7 willcut a hole of a size to allow the nipple to move downwardly but theblades 9 will enlarge this hole to allow the 'free downward descent ofthe drill stem. lVhen the blades become dulled and need repair orreplacement a fishing tool vers or other similar parts which maybeclogffed or broken or interfere with the positive action ot thecutting blades. The blades are projected into cutting position inapositive manner and when the device is to be with drawn there isnothing' to interfere with the ready retraction of the blades so thatthe cut-ters may be withdrawn to the surface for repair. The furtheradvantages-will be obvious to those skilled in the art.

1What I claim as new is:

A well drill including a drill stein, a shoe thereon, a drill nippleslidable within said shoe, a pilot drill at the Jforward end ot saidnipple, cuttingblades in said nipple above said drill, said blades beingpivoted to be swung outwardly from a. normally retracted position insaid nipple tocut a hole ot larger .diameter than said pilot drill, anda` mandrel in said nipple adapted to lit between said blades and irovevthem into cutting position, said bladeshaving straight inner sidesadapted to abut against the said mandrel. for their entire length and bethus held rigidly in expanded position, and vdownwardly projecting legson said shoe to support said blades from their rearward sides duringrotation of said drill and communicate rotation to said pilot drill.

In testimony whereof I hereunto aiiix my signature this 22d day o J une,A. D. 1929.

` SCHUYLER C. KNAUR.

